1. Field of the Invention
This invention relates to independent wheel suspension systems and, more particularly, to independent wheel suspension systems wherein differentials are not rigidly mounted to the vehicle frame.
2. Description of the Prior Art
It is known, as disclosed in the U.S. Pat. No. 2,968,357 to Roller, to reduce the anti-squat of the rear end of a vehicle produced during vehicle acceleration while also isolating roadnoise by allowing a vehicle differential to pivot on resilient bushings supported by a pair of transverse trunnion shafts from the side rails of a vehicle frame. However, the Roller reference also includes an abutment structure preventing rotation of the differential in one direction relative to the support frame while normally restraining motion in the other direction, except under acceleration in excess of a predetermined acceleration. Moreover, the Roller structure also includes the universal coupling between the prop shaft and differential to accommodate momentary changes in the angular inclination of the differential.
The U.S. Pat. No. 3,625,300 to Barenyi and Wilfert discloses the suspension of an axle unit of a motor vehicle by a support member premitting pivoting of the wheel pair in relation to the vehicle super-structure about two mutually perpendicular essentially horizontal axes, but without allowing any relative movement about either axis between the wheels and the axle gear housing.
The present invention recognizes that it is desireable to allow the differential to pivot relative to the frame as the frame undergoes a displacement relative to the driving sufrace between a normal position, a fully loaded position, and an unloaded position. The present invention further recognizes that, wiht the differential free to pivot relative to the support frame, such pivoting can accommodate the function otherwise served by the universal coupling between the prop shaft and the differential to thereby allow the elimination of this universal coupling.
In accordance with the present invention, a pair of pivot pins defining a transverse axis are carried by extension mambers projecting from opposite sides of a differential housing and a pair of journal members mating with these pivot pins are carried by a transverse frame member to allow the differential to pivot about the transverse axis as well as to pivot about the differential output axis. Resilient bushings are interposed between the pivot pins and journal members to dampen engine, differential and road vibrations. A prop shaft couples the engine to the differential, the coupling at the engine end of the prop shaft being of the constant velocity universal type and the coupling at the differential end of the prop shaft being of the sliding splined type. the universal coupling allows the prop shaft to undergo an articulation relative to the engine as the vehicle frame undergoes a displacement relative to the driving surface. This articulation is accommodated by a corresponding pivoting motion of the differential relative to the transverse axis while at the same time keeping the prop shaft axis coaxial with the input axis of the differential.
It is therefore, an object of the present invention to provide a new and improved independent wheel suspension system.
It is another primary object of the present invention to provide a new and improved independent wheel suspension system, wherein the vehicle differential is allowed to pivot relative to a vehicle frame to accommodate articulation between a prop shaft and an engine as the vehicle frame undergoes displacement relative to a driving surface.
It is another primary object of the present invention to provide an independent wheel suspension system having a differential pivotable about more than one axis.
It is a further object of the present invention to provide an independent wheel suspension of the foregoing type, wherein the prop shaft is coupled to the differential by a joint that prohibits articulation between the prop shaft axis and the input axis of the differential.
It is a further object of the present invention to provide an independent wheel suspension system of the foregoing type, wherein the pivot means allowing the differential to pivot relative to the transverse axis of the transverse frame member further includes resilent bushings for dampening vibrations of the engine or differential.
These and other features and objects of the present invention will become more apparent ot those skilled in the art from the following detailed description of a preferred embodiment taken in conjunction with the drawing appended hereto.